Osseointegration is defined clinically as the process whereby clinically asymptomatic rigid fixation of alloplastic materials is achieved and maintained in bone during functional loading. Typical dental implants, when osseointegrated in the upper or lower jaw, provide stable anchorage for dental prostheses. To achieve successful osseointegration, it is normally required that the implant and the bone tissue at the surgical site be brought into close proximity to one another. Over time, as long as the implant remains undisturbed, the implant becomes osseointegrated with the bone. Once the implant has been successfully osseointegrated, the prosthetic devices may then be attached to the implant using the implant as the stable foundation for the prosthesis.
Integration of implants typically involves close fitting of an implant into the surgical site. Integration of the implant into the surgical site is often assisted by various techniques to ensure osseointegration. These may include surface treatment intended to promote osseointegration at a micro level, as well as contouring the surface of the implant to help to achieve osseointegration at a more macro level. Many implants which have been used are provided with a threaded outer surface. The threads of the threaded outer surface act as an aid in the osseointegration procedure.
When placing such typical implants, the oral surgeon must create a suitable socket into which the implant will be placed. This involves drilling a suitable size hole in the host bone. The use of a single drill of the same diameter as the dental implant, at high speed, can lead to necrosis in the bone, and thus much less aggressive techniques for making a suitable hole are typically used. It is standard for an oral surgeon to use three to five successively larger drill sizes to make one final hole of a diameter large enough to accommodate a typical implant. The first drill makes a relatively small hole. Each successive drill has a slightly larger diameter thereby enlarging the bore of the hole to achieve a desired diameter. Once the hole has been enlarged to an acceptable diameter, a dental implant may then be inserted into the hole made in the bone. Such an implant will then rely solely on osseointegration at a micro level between the bone and the surface of the implant for successful integration. In order for such osseointegration to successfully occur, the implant must fit very closely and accurately into the hole drilled in the bone. Obtaining such a close fit is difficult given the variance of each successive drilling procedure due to wobble, etc.
Typically, after the hole has been drilled to a desired diameter, the oral surgeon performs a further step. This further step involves using a tap to cut a thread in the surface of the bore of the hole which has been made using the drills. This produces a screw thread extending helically, proximally into the bone. The term “proximal” will be used in this specification and claims with reference to the bone involved to be the direction or surface which is closest to the centre of the bone representing the surgical site, while the term “distal” will be used to describe the direction or surface which is remote from the centre of the bone. Thus, the tap will create a helical thread extending proximally into the bone.
After the bore of the hole has been subjected to the cutting action of the tap, then an implant having a threaded exterior surface with a thread matching the thread of the tap used, may be screwed into the hole. The surgical site may then be permitted to heal. Over time, the implant will become osseointegrated into the drilled and tapped bone.
Because a non-aggressive drilling and tapping action is required in order to avoid necrosis of bone at the surgical site, the drilling speeds are typically kept quite low, often as low as 15 revolutions per minute.
This extended procedure thus involves, typically, use of as many as five drills followed by a tap, all of which must be operated at relatively slow speeds. This means that the surgical procedure itself involves a plurality of steps, all of which are conducted at relatively slow speeds, which thus prolong the surgical procedure and decrease precision. In addition, the procedure involves use of many components including the set of drills as well as the tap.